>>> class test(object):
...     foo = "bar"
...
>>> del test.foo
>>> bar = test()
>>> print bar.foo
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: 'test' object has no attribute 'foo'
>>> test.haha = "hihi"
>>> print test.haha
hihi
>>> print bar.haha
hihi
>>>